delete the updated data before union two tables (100分)

Hello everybody;

the two tables with all the same fields (over hundred),
table AAA is the archieved data,
table BBB is the live table used for data entry.

question: how to check the data updated in table BBB?
and delete the table AAA the updated data before union two
tables into AAA?

Trigger will be better.
If BBB id updated then delete these records from AAA

接受答案了.